Intraoperative cultures during appendectomy in children are poor predictors of pathogens and resistance patterns in cultures from postoperative abscesses

Use of Antipseudomonal Antibiotics is Not Associated With Lower Rates of Postoperative Drainage Procedures or More Favorable Culture Profiles in Children With Complicated Appendicitis: Results From a Multicenter Regional Research Consortium

OBJECTIVE

To compare rates of postoperative drainage and culture profiles in children with complicated appendicitis treated with the 2 most common antibiotic regimens with and without antipseudomonal activity [piperacillin-tazobactam (PT) and ceftriaxone with metronidazole (CM)].

BACKGROUND

Variation in the use of antipseudomonal antibiotics has been driven by a paucity of multicenter data reporting clinically relevant, culture-based outcomes.

METHODS

A retrospective cohort study of patients with complicated appendicitis (7/2015-6/2020) using NSQIP-Pediatric data from 15 hospitals participating in a regional research consortium. Operative report details, antibiotic utilization, and culture data were obtained through supplemental chart review. Rates of 30-day postoperative drainage and organism-specific culture positivity were compared between groups using mixed-effects regression to adjust for clustering after propensity matching on measures of disease severity.

RESULTS

In all, 1002 children met the criteria for matching (58.9% received CM and 41.1% received PT). In the matched sample of 778 patients, children treated with PT had similar rates of drainage overall [PT: 11.8%, CM: 12.1%; odds ratio (OR): 1.44 (OR: 0.71-2.94)] and higher rates of drainage associated with the growth of any organism [PT: 7.7%, CM: 4.6%; OR: 2.41 (95% CI: 1.08-5.39)] and Escherichia coli [PT: 4.6%, CM: 1.8%; OR: 3.42 (95% CI: 1.07-10.92)] compared to treatment with CM. Rates were similar between groups for drainage associated with multiple organisms [PT: 2.6%, CM: 1.5%; OR: 3.81 (95% CI: 0.96-15.08)] and Pseudomonas [PT: 1.0%, CM: 1.3%; OR: 3.42 (95% CI: 0.55-21.28)].

CONCLUSIONS AND RELEVANCE

The use of antipseudomonal antibiotics is not associated with lower rates of postoperative drainage procedures or more favorable culture profiles in children with complicated appendicitis.

Intraoperative bacterial cultures fail to reliably predict the bacterial spectrum encountered during infectious complications after appendicitis

Acute appendicitis is a common surgical emergency. Complicated appendicitis usually warrants perioperative antibiotic treatment in order to prevent infectious complications. Whether routine microbiological testing benefits the individual patient is a topic of debate. The goal of our study was to assess perioperative antibiotic prescriptions as well as the benefit of microbiological testing during the appendectomy as a predictor for bacteria encountered in infectious complications. This is a retrospective analysis of 1218 consecutive patients that underwent appendectomy at a tertiary referral center between 2014 and 2021. The patient charts were systematically analyzed regarding intraoperative outcome, microbiologic results, and postoperative infectious complications. 1218 patients were included in this study of which 768 were uncomplicated appendicitis (UA) and 450 were complicated appendicitis (CA). Microbiological testing was performed in 39.2% of UA cases (33.6% of which grew bacteria) compared to 74.9% of CA cases (78.6% positive cultures). The strongest individual predictors for SSI were gangrenous and perforated appendicitis. A total of 58 surgical-site infections developed, of which 49 were intra-abdominal fluid collections or abscesses. Thirty-two patients had revision surgery or CT-guided drainage for SSI. In the cases where microbiological testing was done both during the appendectomy and the SSI, 13/18 showed different bacteria on culture testing. The infectious outcome was favorable in 98.3%. While microbiological testing offers insights into resistance patterns, it is of little benefit for the individual patient, given the low predictive value for bacteria found during SSI. Achieving source control combined with empiric antibiotic coverage leads to favorable outcomes independent of culture results.

Using Microbiology Culture in Pediatric Appendicitis to Risk Stratify Patients: A Cohort Study

Background: We sought to investigate the value of intra-operative microbiology samples in pediatric appendicitis. Proposed benefits include tailoring post-operative antimicrobial management, risk-stratifying patients, and reducing post-operative intra-abdominal abscess formation. Patients and Methods: All cases of appendicitis managed with appendicectomy in a single center were collected from January 2015 to August 2020. Intra-operative microbiology samples were taken routinely. Post-operative outcomes were analyzed with reference to culture and sensitivity results. Histologic findings were further categorized as normal, simple, or complex. Results: Six hundred seventy-eight children had appendicectomies, and 608 had both microbiology and histology samples taken. Intra-abdominal fluid collection and subsequent intervention rates were 22% and 9%, respectively. There were more collections in those with a culture positive result (p < 0.001), and those growing each of three recognized organisms, Escherichia coli (p < 0.001), Pseudomonas aeruginosa (p = 0.01), and Streptococcus anginosus group (p < 0.001). Intervention rate was higher in the culture-positive result group (p = 0.002) and the Streptococcus anginosus group (p < 0.001). Conclusions: This study shows an increased risk of developing a collection with the isolation of one of three key organisms (Escherichia coli, Pseudomonas aeruginosa, Streptococcus anginosus group). Sersoal swabs are an effective and practical method of gathering information on organisms. Microbiologic yield was correlated to the severity of appendicitis. Isolation of Streptococcus anginosus increases the incidence of collections to 50%. This is useful to empower surgeons to prognosticate patients' potential outcomes based on both intra-operative, and microbiologic findings, and is useful in counseling patients and managing expectations. A prolonged course of antibiotic agents or higher dose may mitigate this risk.

Differences in isolated bacteria between perforated and non-perforated appendicitis: an analysis of 680 consecutive appendicectomies in a single institution

PURPOSE

Escherichia coli and Bacteroides species are the most frequently detected species in ascites in perforated appendicitis and are generally sensitive to non-empiric cephalosporins like cefazolin or cefmetazole. However, monotherapy with such antibiotics is mostly insufficient for perforated appendicitis. To investigate this issue, this study aimed to compare bacterial floras in ascites culture between perforated and non-perforated appendicitis.

METHODS

Ascites culture results in perforated and non-perforated appendicitis cases were analyzed using a departmental database. The duration of symptoms before surgery, pre-surgical white blood cell count, C-reactive protein value, postsurgical length of stay, length of antibiotic treatment, and the rate of using second-line antibiotics or complications were also compared.

RESULTS

A total of 608 and 72 cases of non-perforated and perforated appendicitis were included. Escherichia coli and Bacteroides species were the dominant bacteria in both conditions. However, the total proportions of Pseudomonas aeruginosa, Streptococcus anginosus group, and Enterococcus group were significantly higher in perforated appendicitis than in non-perforated appendicitis.

CONCLUSION

Pseudomonas aeruginosa, Streptococcus anginosus group, and Enterococcus group have better susceptibility to penicillin-based empiric antibiotics than cephalosporins. The abundance of these bacteria might explain why non-empiric cephalosporins are not effective in perforated appendicitis and the superiority of penicillin-based empiric antibiotics.

Antibiotic resistance is common in the cultures of intraabdominal abscess drainage after appendectomy

INTRODUCTION

Intraabdominal abscesses (IAA) are a common complication following appendectomy. Empiric antibiotic regimens may fail to prevent IAA due to changes in bacterial resistance. We aim to describe the bacteriology of pediatric patients requiring drainage of an IAA after an appendectomy for appendicitis.

METHODS

We performed a retrospective study of patients ≤18 years who underwent percutaneous drainage of an IAA following appendectomy a single U.S. children's hospital between 2015 and 2018. Patient demographics, appendicitis characteristics, antibiotic regimens, and culture data were collected.

RESULTS

In total, 71 patients required drainage of an IAA of which 48 (67%) were male, the average age was 9.81 (SD 3.31) years and 68 (95.7%) having complicated appendicitis. Ceftriaxone/metronidazole was the most common empiric regimen prior to IAA drainage occurring in 64 (90.1%) patients. IAA cultures isolated organisms in 34 (47.9%) patients. Of those with positive cultures, 17 (50%) cases demonstrated an antimicrobial resistant organism. Most notably, 20% of Escherichia coli was resistant to the empiric regimen. Empiric antimicrobial regimens did not appropriately cover 92.3% of Pseudomonas aeruginosa cultures or 100% of Enterococcus species cultures. Antimicrobial regimens were changed following IAA drainage in 30 (42.2%) instances with 23 (32.4%) instances due to resistance in culture results or lack of appropriate empiric antimicrobial coverage.

CONCLUSIONS

IAA culture data following appendectomy for appendicitis frequently demonstrates resistance to or lack of appropriate coverage by empiric antimicrobial regimens. These data support close review of IAA culture results to identify prevalent resistant pathogens along with local changes in resistance.

LEVEL OF EVIDENCE

Level III.

Are We Hitting the Target?: The Effectiveness of Distinct Antibiotic Regimens in Pediatric Appendectomies

BACKGROUND

Currently, a range of different antibiotics are administered perioperatively during appendectomy surgery in the pediatric population. One reason for the lack of a uniform treatment regimen is the paucity of large studies on microbiologic data and susceptibility patterns.

METHODS

A retrospective, monocentric study on antibiotic susceptibility, including 1258 pediatric patients undergoing appendectomy from 2012 to 2020 was performed. Predictors for prolonged length of stay (LOS) and complications were determined using regression analysis, and objective criteria for broad-spectrum antibiotic regimens were identified. Simulations of the effectiveness of different antibiotic regimens against identified bacterial susceptibility results were conducted.

RESULTS

The most important predictors for prolonged LOS and an increased incidence of infectious complications are elevated preoperative C-reactive protein levels, high intraoperative severity gradings and insufficient primary antibiotic treatment. Based on our results, a simple antibiotic treatment, consisting of cefuroxime-metronidazole (C-M) or ampicillin-sulbactam (AS), is sufficient in around 85% of all patients; both options being equally efficient. In severe appendicitis, the likelihood of resistance is 31% and 32% for C-M and AS, respectively. For piperacillin-tazobactam and C-M-tobramycin, the incidence of bacterial resistance decreases to 12%. Resistance is reduced to 8% for AS-tobramycin treatment. The patient populations benefiting most from an extended antibiotic regimen are those with a high intraoperative severity grading.

CONCLUSIONS

Evidence suggests that an insufficient antibiotic regimen is associated with a prolonged LOS and a higher rate of infectious complications, justifying the expansion of a simple antibiotic regimen in cases of severe intraabdominal findings. In all other cases, a simple antibiotic treatment with AS is recommended.

Postoperative organ space infection (OSI) following appendectomy: early term evaluation for pediatric population

No consensus has been reached on the duration of antibiotic prophylaxis for postoperative organ space infection (OSI) following appendectomy. This study investigated the influence of antibiotic administration on postoperative OSIs in children with complex appendicitis. A multicenter, retrospective study was conducted in patients with OSI following complicated appendicitis between 2017 and 2019 at 3 hospitals in China. The qualified patients were dichotomized into a long-duration antibiotic group (> 5.5 days) and a short-duration antibiotic group (< 5.5 days) based on the median duration (5.5 days) of antibiotic administration. Potential biases in baseline characteristics were managed using propensity score matching for the two groups. Primary and secondary outcomes were compared between the two groups. Propensity-matched analysis of the entire cohort revealed no significant effects in terms of the time to OSI resolution (p = 0.16) or recurrence (p = 0.22) for the short-duration and long-duration antibiotic groups. A slightly lower complication rate, including the incidence of abdominal distention (p = 0.093) and antibiotic-associated diarrhea (p = 0.024), was noted in patients with short-duration antibiotic administration. Furthermore, no significant difference in readmission requirements (p = 0.14) or hospitalization duration (p = 0.102) was found between the two groups. For OSI following complicated appendicitis, long-term antibiotic administration did not provide a significant benefit.

Clinical, Laboratory and Radiographic Features Associated With Prolonged Hospitalization in Children With Complicated Appendicitis

OBJECTIVE

In children with appendicitis, rupture of the appendix is associated with a significant increase in morbidity. We sought to characterize the spectrum of illness in children with complicated appendicitis and to define those factors associated with a longer hospital stay.

STUDY DESIGN

We conducted a retrospective review of 132 children, 18 years of age or younger at a large urban teaching hospital in the Bronx, NY between October 2015 and April 2018 with an intraoperative diagnosis of perforated appendix. Clinical, laboratory and radiologic findings were reviewed, and the primary study outcome was length of stay (LOS) dichotomized at the median, which was 7 days. Statistical analyses were done to characterize morbidity and define variables predictive of longer stay.

RESULTS

Children in the longer LOS group experienced significantly more morbidity, including ICU stay, ileus, and need for multiple drainage procedures. A longer duration of symptoms prior to presentation was associated with a longer stay. Multivariable logistic regression analysis indicated that the presence of abscess and presence of free fluid in the right upper quadrant (RUQ FF) on initial imaging and C-reactive protein (CRP) level >12 at admission, were independently associated with a longer stay.

CONCLUSION

There is considerable variation in the morbidity of complicated appendicitis. The association between longer stay and the findings of abscess and RUQ FF on initial imaging along with an elevated CRP may provide a useful tool in identifying those children at risk for worse outcomes.

Reduction of surgical site infections in pediatric patients with complicated appendicitis: Utilization of antibiotic stewardship principles and quality improvement methodology

BACKGROUND

The rate of surgical site infection (SSI) after appendectomy for complicated appendicitis (CA) was high at our children's hospital. We hypothesized that practice standardization, including obtaining intra-operative cultures of abdominal fluid in patients with CA, would improve outcomes and reduce healthcare utilization after appendectomy.

METHODS

A quality improvement team designed and implemented a clinical practice guideline for CA that included obtaining intra-operative culture of purulent fluid, administering piperacillin/tazobactam for at least 72 h post-operatively, and transitioning to oral antibiotics based on intraoperative culture data. We compared outcomes before and after guideline implementation.

RESULTS

From July 2018-October 2019, 63 children underwent appendectomy for CA compared to 41 children from January-December 2020. Compliance with our process measures are as follows: Intra-operative culture was obtained in 98% of patients post-implementation; 95% received at least 72 h of piperacillin-tazobactam; and culture results were checked on all patients. Culture results altered the choice of discharge antibiotics in 12 (29%) of patients. All-cause morbidity (SSI, emergency department visit, readmission to hospital, percutaneous drain, unplanned return to operating room) decreased significantly from 35% to 15% (p=0.02). Surgical site infections became less frequent, occurring on average every 27 days pre-implementation and every 60 days after care pathway implementation (p=0.03).

CONCLUSIONS

Utilization of a clinical practice guideline was associated with reduced morbidity after appendectomy for CA. Intra-operative fluid culture during appendectomy for CA appears to facilitate the selection of appropriate post-operative antibiotics and, thus, minimize SSIs and overall morbidity.

Optimal First-Line Antibiotic Treatment for Pediatric Complicated Appendicitis Based on Peritoneal Fluid Culture

PURPOSE

Consensus is lacking regarding the optimal antibiotic treatment for pediatric complicated appendicitis. This study determined the optimal first-line antibiotic treatment for pediatric patients with complicated appendicitis based on peritoneal fluid cultures.

METHODS

This retrospective study examined the cases of pediatric patients who underwent appendectomy for complicated appendicitis at our institution between 2013 and 2019. Peritoneal fluid specimens obtained during appendectomy were cultured for the presence of bacteria.

RESULTS

Eighty-six pediatric patients were diagnosed with complicated appendicitis. Of them, bacteria were identified in 54 peritoneal fluid samples. The major identified bacteria were Escherichia coli (n=36 [66.7%]), Bacteroides fragilis (n=28 [51.9%]), α-Streptococcus (n=25 [46.3%]), Pseudomonas aeruginosa (n=10 [18.5%]), Enterococcus avium (n=9 [16.7%]), γ-Streptococcus (n=9 [16.7%]), and Klebsiella oxytoca (n=6 [11.1%]). An antibiotic susceptibility analysis showed E. coli was inhibited by sulbactam/ampicillin in 43.8% of cases versus cefmetazole in 100% of cases. Tazobactam/piperacillin and meropenem inhibited the growth of 96.9-100% of the major identified bacteria. E. coli (100% vs. 84.6%) and P. aeruginosa (100% vs. 80.0%) were more susceptible to amikacin than gentamicin.

CONCLUSION

Tazobactam/piperacillin or meropenem is a reasonable first-line antibiotic treatment for pediatric complicated appendicitis. In the case of aminoglycoside use, amikacin is recommended.

Management and Microbiology of Perforated Appendicitis in Pediatric Patients: A 5-Year Retrospective Study

INTRODUCTION

This study aims to assess the current epidemiology and microbiology of perforated appendicitis, how antibiotic choice and duration correlate with meaningful clinical outcomes, and whether serial white blood cell (WBC) counts provide clinical value.

METHODS

Five-year retrospective cohort study, 2015-2019, among 333 consecutive children, ages 0-18 years, treated at St. Louis Children's Hospital for perforated appendicitis. Main outcomes included length of stay (LOS), postoperative abscess formation, and readmission. Statistical analysis was performed with uni- and multi-variate analyses.

RESULTS

Intra-abdominal cultures most commonly grew Bacteroides fragilis (52%) and Escherichia coli (50%). Patients who initially received broad-spectrum antibiotics (meropenem, piperacillin-tazobactam, fourth-generation cephalosporins) for perforated appendicitis had greater rates of postoperative abscess formation (25% vs. 12%, p < 0.01) and LOS (7.0 vs. 5.7 days, p < 0.01). Similarly, antibiotics at time of discharge were associated with greater postoperative abscess formation (22% vs. 9%, p < 0.01) and LOS (6.4 vs. 5.6 days, p = 0.02). However, discharge with strictly oral antibiotics was not correlated with greater LOS, postoperative abscess formation, or readmission rates compared to discharge without antibiotics. Serial WBC counts had no predictive value for LOS, postoperative abscess formation, or readmission.

CONCLUSIONS

Bacteroides fragilis and E. coli were the most common intra-abdominal microbes for perforated appendicitis among our cohort. In non-critically ill children, the routine use of broad-spectrum antibiotics or continuation of antibiotics beyond discharge was not correlated with improved clinical outcomes. Additionally, WBC counts were not correlated with meaningful clinical outcomes.

The intraperitoneal bacteriology and antimicrobial resistance in acute appendicitis among children: a retrospective cohort study between the years 2007-2017

This study aims to describe the microbiology and susceptibility profile of the intraperitoneal flora in complicated appendicitis. It is a retrospective cohort study including children < 18-year-old with pathologically confirmed appendicitis, from 2007 to 2017. It included 1466 children. Intraperitoneal samples were obtained from 655 (44.7%) patients, and 201 (30.7%) had positive culture with 395 pathogens. Gram-negative rods comprised 67.6%, Gram-positive cocci 21.5%, and anaerobes 10.9% of the isolates. Gram-positive cocci were detected in 67 (37.8%) patients. Milleri group Streptococci was the most frequently isolated Gram-positive (44.7%). The proportional rate of Milleri group Streptococci from Gram-positive cocci increased from 9.5 to 56.3% (P < 0.001, OR 12.214). Patients with Gram-positive cocci had longer hospital stay (mean 9.36 + 6.385 vs 7.72 + 4.582, P = 0.036, (CI -3.165, -0.105)) and more complicated disease (89.5% vs 78.4%, P = 0.045, OR 2.342). Patients with Milleri group Streptococci isolates readmitted more frequently (26.5% vs 13.2%, P = 0.05, OR 2.37). Resistance to amoxicillin-clavulanate, gentamicin, ceftazidime, piperacillin-tazobactam, and amikacin were detected in 29.1%, 6.5%, 2.3%, 1.2%, and 0.7% of the Gram-negative rods, respectively.Conclusion: The rates of Gram-positive cocci and particularly Milleri group Streptococci in peritoneal fluid are increasing. More complicated disease and longer hospital stay in Gram-positive cocci and higher readmission rate in Milleri group Streptococci. These emphasize the role of anti-Gram-positive antimicrobials. What is known: • Gram-negative rods are the main isolates in complicated appendicitis. • The choice of antibiotic regimen is an unsettled issue due to resistance. What is new: • Increased rate of Gram-positive cocci and Milleri group Streptococci. • More complicated disease, longer hospital stay, and higher readmission rate.

Usefulness of intraoperative culture swabs in laparoscopic appendectomy for complicated appendicitis

PURPOSE

Intraabdominal abscess (IAA) is a feared complication after laparoscopic appendectomy (LA) for complicated appendicitis. Benefits of obtaining intraoperative culture swabs (ICS) still remain controversial. We aimed to determine whether ICS modify the rate and management of IAA after LA for complicated appendicitis.

METHODS

A consecutive series of patients who underwent LA for complicated appendicitis from 2008 to 2018 were included. The cohort was divided into two groups: group 1 (G1), with ICS, and group 2 (G2), without ICS. Demographics, operative variables, pathogen isolation, antibiotic sensitivity, and postoperative outcomes were analyzed.

RESULTS

A total of 1639 LA were performed in the study period. Of these, 270 (16.5%) were complicated appendicitis; 90 (33%) belonged to G1 and 180 (67%) to G2. In G1, a higher proportion of patients had generalized peritonitis (G1, 63.3%; G2, 35%; p < 0.01). Seventy-two (80%) patients had positive cultures in G1. The most frequently isolated bacteria were E. coli (66.7%), Bacteroides spp. (34.7%), and Streptococcus spp. (19.4%). In 26 (36%) patients, the initial empiric antibiotic course was modified due to bacterial resistance. The rate of IAA was higher in patients with ICS (G1, 21.1%; G2, 9.4%; p = 0.01). IAA was treated similarly in both groups. A different type of bacteria was isolated in 7 (53.8%) patients with new culture swabs.

CONCLUSIONS

Obtaining ICS in LA for complicated appendicitis with further antibiotic adjustment to the initial pathogen did not lower the incidence of postoperative IAA and did not modify the treatment needed for this complication.

Sensibilidad antimicrobiana en aislamientos de líquido peritoneal de niños intervenidos por abdomen agudo e infección intraabdominal

Introducción. La apendicitis aguda es causa frecuente de infección intraabdominal en pediatría. La elección del antibiótico se basa en los hallazgos quirúrgicos macroscópicos, el criterio médico, las guías locales o internacionales y, en pocas ocasiones, en el resultado de los aislamientos bacterianos en cultivos de líquido peritoneal y las tasas locales de resistencia. Se analizaron la frecuencia y la sensibilidad microbiológica de los cultivos de muestras de líquido peritoneal de pacientes de un mes a 16 años de edad con manejo quirúrgico por abdomen agudo con sospecha de infección intraabdominal. Materiales y métodos. Se llevó a cabo un estudio prospectivo de cohorte con análisis de las historias clínicas y de resultados de laboratorio de niños sometidos a cirugía por abdomen agudo, en la que el cirujano tomó muestra del líquido peritoneal para la tipificación y determinación de los perfiles de sensibilidad de los microorganismos aislados. Los datos se analizaron con el programa Stata™, versión15.0. Resultados. Se identificaron 303 casos, de los cuales el 93,6 % recibió profilaxis antibiótica con ampicilina-sulbactam y clindamicina-amikacina. El 95,3 % de los procedimientos fueron apendicectomías. Se tomó cultivo del 50 % de las apendicitis perforadas. Se aislaron 48 microorganismos; el más frecuente (2,7 %) fue Escherichia coli positiva para BLEE. El 100 % de los microorganismos resultaron ser sensibles a la amikacina, el 97,2 % al meropenem, y el 94,4 %, a la ciprofloxacina, el cefepime y el ceftazidime. La resistencia más frecuente (37,1 %) fue contra la combinación de ampicilina y sulbactam, en los gérmenes Gram negativos. Discusión. La evaluación de la sensibilidad antimicrobiana de los aislamientos de líquido peritoneal de los procedimientos quirúrgicos en pediatría, es una buena práctica clínica que orienta al cirujano en la adecuada selección del esquema antibiótico y, además, disminuye el riesgo de falla terapéutica temprana y la posibilidad de mayor resistencia o complicaciones infecciosas.